Engine fuel supply system

Abstract

A fuel supply system for providing fuel from a fuel source to a combustion chamber of an engine is disclosed. The fuel supply system includes a vapor separator in which vapor is separated from fuel supplied from the fuel source. A pre-pressurizing pump pressurizes fuel from the vapor separator to a first pressure and delivers it to a high pressure pump. The high pressure pump pressurizes the fuel to a pressure above the first pressure and delivers it to a fuel rail to which is connected a fuel injector for delivering fuel into the combustion chamber. A fuel return line extends from the fuel rail for returning undelivered fuel back to the fuel system. A valve controls the flow of fuel through the return line and maintains the fuel at high pressure in the fuel rail. A fuel cooler is provided along the return fuel line.

What is claimed is: 
     
       1. A fuel supply system for supplying fuel from a fuel source to an engine powering an outboard motor, the engine having at least one combustion chamber, said fuel supply system comprising a vapor separator to which fuel is delivered from the fuel source for separation of vapor from the fuel, a pre-pressurizing pump for pressurizing fuel from the separator and delivering said fuel at a first pressure above a pressure of said fuel within said vapor separator to a high pressure pump, said high pressure pump pressurizing said fuel to a pressure above said first pressure and delivering said fuel to a fuel rail through which fuel is delivered to said fuel injector for delivery into said combustion chamber, a return line extending from said fuel rail to said vapor separator for returning fuel delivered to said fuel rail but not delivered by said fuel injector back to said vapor separator, an adjustment valve for regulating the flow of fuel through said return line and maintaining the fuel in said fuel rail at high pressure, and further including a fuel cooler positioned between said adjustment valve and said vapor separator along said return line for cooling said fuel passing therethrough. 
     
     
       2. The fuel supply system in accordance with claim 1, further including a relief valve for relieving fuel over a predetermined high pressure from the fuel system between said pre-pressurizing pump and said high pressure pump back to said vapor separator. 
     
     
       3. The fuel supply system in accordance with claim 1, wherein said pre-pressurizing pump is positioned within said vapor separator. 
     
     
       4. The fuel supply system in accordance with claim 1, wherein said fuel cooler comprises a water-cooled vapor separator. 
     
     
       5. The fuel supply system in accordance with claim 1, including a control operating said pre-pressurizing pump at a low speed when a speed of said engine is low. 
     
     
       6. The fuel supply system in accordance with claim 1, wherein at least a portion of the fuel supplied by said pre-pressurizing pump to said high pressure pump is returned through a line back to said vapor separator. 
     
     
       7. The fuel supply system in accordance with claim 1, wherein at least a portion of the fuel supplied by said pre-pressurizing pump passes through a fuel cooler and is returned to said vapor separator. 
     
     
       8. A fuel supply system for supplying fuel from a fuel source to an engine powering an outboard motor, the engine having at least one combustion chamber, said fuel supply system comprising a vapor separator to which fuel is delivered from the fuel source for separation of vapor from the fuel, a pre-pressurizing pump for pressurizing fuel from the separator and delivering said fuel at a first pressure above a pressure of said fuel within said vapor separator to a high pressure pump, said high pressure pump pressurizing said fuel to a pressure above said first pressure and delivering said fuel to a fuel rail through which fuel is delivered to said fuel injector for delivery into said combustion chamber, a return line extending from said fuel rail to a point along said fuel system after said pre-pressurizing pump for returning fuel delivered to said fuel rail but not delivered by said fuel injector, an adjustment valve for regulating the flow of fuel through said return line and maintaining the fuel in said fuel rail at high pressure, and further including a fuel cooler positioned along said return line for cooling said fuel passing therethrough. 
     
     
       9. The fuel supply system in accordance with claim 8, wherein said pre-pressurizing pump is operated at a low speed if a speed of said engine is low. 
     
     
       10. The fuel supply system in accordance with claim 8, wherein said valve is pressure operated and positioned along said second fuel line. 
     
     
       11. The fuel supply system in accordance with claim 8, wherein said second fuel line leads to a first end of said fuel rail and said valve is pressure operated at positioned at a second end of said fuel rail. 
     
     
       12. The fuel supply system in accordance with claim 8, further including a fuel cooler positioned along said fuel supply system between said vapor separator and said second pump. 
     
     
       13. The fuel supply system in accordance with claim 8, further including a fuel filter positioned along said fuel supply system between said second pump and said fuel injector. 
     
     
       14. The fuel supply system in accordance with claim 8, wherein at least a portion of the fuel supplied by said pre-pressurizing pump to said high pressure pump is returned through a line back to said vapor separator. 
     
     
       15. The fuel supply system in accordance with claim 8, wherein at least a portion of the fuel supplied by said pre-pressurizing pump passes through a fuel cooler and is returned to said vapor separator.